As an alternative to more invasive types of surgical procedures, many physicians are employing the use of High Intensity Focused Ultrasound (HIFU) as a technique to therapeutically treat internal body tissues. With HIFU, an ultrasound signal of sufficient power (pressure and particle velocity) and time is focused on a target volume of tissue in order to change a state of the tissue by heating and/or by cavitation.
To be effective in treating tissue, the delivered energy of the HIFU signal must be sufficient to cause the desired physical effect. Additionally, the energy must not be so great or uncontrolled as to cause unintended collateral damage to healthy tissues surrounding the target volume. The non-homogenous nature of tissue(s) in the body creates variations in attenuation, propagation velocity, and acoustic impedance that modify the expected acoustic wave propagation and deposition of HIFU energy delivered to a target tissue volume when compared to homogeneous material. The technology disclosed herein is a method and apparatus for dynamically controlling and/or selecting parameters that affect the energy of a HIFU signal and/or the location where the energy is directed so that the desired physical effect in tissue is obtained and collateral damage to surrounding tissue is minimized.